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Details

Numéro d'artefact
2002.0291.015
contexte Fonction
USED TO MEASURE LATITUDE, AND FOR TIME DETERMINATION.
contexte technique
PZT IS VERTICALLY MOUNTED TELESCOPE USING POOL OF MERCURY AT BOTTOM TO ENSURE THE LINE OF SIGHT IS EXACTLY TO/AT THE ZENITH. CONCEIVED BY SIR GEORGE AIRY IN 1854, THE 1ST PZT WAS BUILT C.1909 BY FRANK ROSS. IN 1911 IT WAS PLACED IN OPERATION IN MARYLAND FOR USE BY THE US COAST & GEODETIC SURVEY. BY 1960, 9 OTHERS WERE BUILT & INSTALLED IN OBSERVATORIES AROUND THE WORLD. (REF. 1)
contexte Canada
2ND, LATER PHOTOGRAPHIC ZENITH TELESCOPE (PZT) BUILT AT US NAVAL OBSERVATORY C. 1967-8, AND USED AT DOMINION OBS. IN OTTAWA UNTIL EARLY 1990S. IT REPLACED ORIGINAL PZT BUILT IN 1951 BY DOMINION OBSERVATORY SHOPS (PRECISION COMPONENTS); VICKERS LTD., MONTREAL (CASTINGS); AND PERKIN ELMER CO., GLENBROOK, CT (OBJECTIVE). ( REF.1)
Description
METAL (BRASS AND/OR BRONZE); .15PTS: COVERS & INSERT: CARDBOARD
Nombres de pièces
42
Fini(s) de l'artefact
Brass and/or bronze gear has 6 medium size holes and 2 pin-hole size holes surrounding single large central hole; toothed outer surface of disk interrupted by 2 smooth section. Gear sandwiched between 2 cardboard covers; central insert also made of cardboard. All marked .15 PTS.
Marques sur l'artefact
No legible markings visible; "x" (?) handwritten in black marker on one side of gear. .15pt gear: Top cover bears white label marked "BRASS GEAR/ FOR P.Z.T. REVERSAL".
Groupe 1
Astronomie
Catégorie 1
Équipement d'observation
Sous-catégorie 1
Télescopes optiques
Matériau(x)
métal->;papier->carton